Connecting to projector via display port

I have been using the display port on W700 via HDMI cable to connect to my projector OK and then next day can not get either to talk to each other. What might be wrong? Have tried connecting both in alternate ways with cable - switching one and then other etc to no avail. I did go to Presentation Director after using both and ticked "Capture Display settings" but unticking etc makes no difference and finally I uninstalled PD and reinstalled.